JPH084820B2 - Plate warpage control method in plate rolling - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a method for controlling plate warpage in plate rolling,
In particular, the present invention relates to an improvement in a plate warpage control method in thick plate rolling, which is suitable for use in thick plate rolling by a reverse rolling mill.

[Prior art]

Vertical warpage at the platen rear end in thick plate rolling causes reduction of rolling efficiency due to the inability to bite the rolling mill, damage to equipment, occurrence of residual strain, quality deterioration due to uneven cooling, etc.
It causes a great deal of real harm. In this way, the above-mentioned vertical warpage that causes serious damage is the temperature difference between the upper and lower surfaces of the material to be rolled and the friction state, the difference between the upper and lower work roll diameters, the plate thickness and the rolling reduction, the pick-up amount of the lower work roll, the Many factors such as vertical impact drop amount and difference when biting rolled material are involved.
Therefore, it is difficult to quantitatively elucidate the influence of each of the above factors on the vertical warp of the thick plate, and it is difficult to appropriately control the plate warp. Further, the occurrence of plate warpage is limited to the unsteady region at the rear end of the plate front, which is one of the factors that make it difficult to quantitatively grasp and control the factors of plate warp. For this reason, conventionally, as a method of eliminating the vertical warp of the plate, a method of controlling the rotation speed of the upper and lower work rolls
59-129409), one that controls the amount of pick-up of the lower work roll (JP-A-59-178114), one that controls the amount of upper and lower impact drops, and one that controls the temperature difference between the upper and lower surfaces of the rolled material ( The respective controls of JP-A-57-88909) and the like are performed independently. For example, as a method of correcting the warp, Japanese Patent Laid-Open No. 57-88
As proposed in 909, there is one that detects the temperature of the upper and lower surfaces of the plate and corrects the warp based on this temperature information. The amount of pick-up of the lower work roll is
As shown in FIG. 14, it is the difference H between the lower work roll 1 and the top surface level and the top surface level of the table rollers 2 installed on the front and rear surfaces of the rolling mill. Further, the upper and lower impact drop means a phenomenon in which the rotational speeds of the upper and lower work rolls temporarily decrease when the plate is engaged, as shown in FIG. 15, and the impact drop amount means It is defined as the ratio n / N ₀ of the maximum value n of the rotation speed drop amount of the upper and lower work rolls in the impact drop generation region and the rotation speed N ₀ of the upper and lower work rolls before the plate is caught.

[Problems to be Solved by the Invention]

However, as shown in FIG. 16, the warp shape of the thick plate 3 is such that the warp shown in FIG. 16A, the warp shown in FIG. A so-called tip nose bend, in which only the tip portion is bent with a large curvature, a composite type of upward warp and tip nose bend shown in FIG. 7D, and a composite type of downward warp and tip nose bend shown in FIG. However, these factors also differ depending on the warp shape, and optimal warp control corresponding to various warp shapes has not been performed. Therefore, there is a problem that it is not possible to reliably suppress the vertical warp of the thick plate 3. Further, in the forming pass due to a problem in rolling, the above-mentioned pick-up amount control of the lower work roll cannot be performed, and the effect of the rotation speed control and the temperature difference control also changes due to the change of the plate thickness and the rolling reduction. The above-mentioned conventional means has a problem that it is impossible to reliably prevent the vertical warp of the plate.

[Object of the invention]

The present invention has been made in view of the above conventional problems, among various warp control means, according to the rolling conditions,
It is an object of the present invention to provide a plate warpage control method in thick plate rolling that allows the most effective warpage control means to be selected for warpage control and therefore enables efficient control.

[Means for solving problems]

The present invention is based on a warp amount and a warp shape measurement result of a warp sensor installed on at least one of the front and rear surfaces of a rolling mill of a thick plate rolling mill and quantifying the vertical warp of the thick plate, and the vertical warp of the plate tip portion. In the plate warpage control method for thick plate rolling that corrects the above, as shown in the outline of FIG. 1, it is determined whether or not it is a forming pass, and the contact arc length between the rolling material and the roll and the average plate thickness of the rolling material. Of the upper and lower work rolls, the control of the lower work roll pick-up amount, the upper and lower impact drop amount control, and the thick plate The above object is achieved by selecting either the lower surface temperature difference control or a combination thereof.

[Action]

The inventor conducted a theoretical study on the mechanism of warpage, and the warpage was quantified by using the ratio ld / hm of the contact arc length (ld) of the material to be rolled and the average plate thickness (hm) of the material to be rolled. Can be converted. That is, the present invention has been completed based on the new knowledge that the warp amount and the direction can be estimated if the control amount of the warp control means and ld / lm are known. Further, based on this knowledge, it becomes possible to select the most effective warp control means for warp control, and it becomes possible to perform efficient control. Here, the contact arc length ld and the average strip thickness hm are, for example, as described in “Logic and Practice of Strip Rolling”, pages 7 and 10 issued by Japan Iron and Steel Institute Joint Research Group, Rolling Theory Section. Then, it can be predicted as follows. That is, as shown in FIG. 2, the work roll of the material 16 to be rolled
Set the entry side plate thickness to 10 to H ₀ and the exit side plate thickness to H _1, and set the work roll
Assuming that the flat roll radius of 10 is R ′ and Δh = H ₀ −H ₁ , the (projected) contact arc length ld is expressed by the following equation. The average plate thickness hm is expressed by the following equation. hm≈ (H ₀ + 2H ₁ ) / 3 (2) Here, the input side plate thickness H ₀ and the output side plate thickness H ₁ can be measured values or calculated values by a gauge meter formula.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 3, the plate rolling equipment for carrying out the plate warpage control method in plate rolling according to the present invention includes work rolls 10 and 11 and a back-up cap which rotates in contact with the work rolls 10 and 11. A reverse rolling mill 14 provided with rolls 12 and 13, and a cooling device 18A arranged on the inlet side and the outlet side of the reverse rolling mill 14 for cooling the rolled material 16 by injecting cooling water to the rolled material 16. , 18B, 20A, 20B and these cooling devices 18
A flow rate control device 22 for controlling the flow rate of the cooling water of A ~ 20B, and electric motors 24, 25 for rotationally driving the work rolls 10, 11;
A main engine control device 26 for controlling these electric motors 24, 25, a hydraulic cylinder 28 installed in the back-up roll 13, and
A hydraulic pressure reduction control device 30 for controlling the hydraulic cylinder 28,
A warp sensor 32 for detecting the warp amount and warp shape of the front and rear ends of the material 16 to be rolled rolled by the reverse rolling mill 14,
A micro computer 34 that processes the detection signal from the warp sensor 32, an upper surface thermometer 36 that detects the upper surface temperature of the material 16 to be rolled, a lower surface thermometer 38 that detects the lower surface temperature of the material 16 to be rolled, and It comprises a flow controller 22 for the cooling water, a main engine controller 26, and a process computer 40 for controlling the hydraulic pressure controller 30 based on the output signals of the microcomputer 34, thermometers 36, 38. The process computer 40 includes a path schedule,
Based on the warp amount and the warp shape at the tip of the rolled material 16 obtained from the micro computer 34, the rotation speed control of the upper and lower work rolls, the pick up amount control of the lower work roll, the upper and lower impact drop amount control, the rolled material Of the upper surface temperature difference control of 16, while selecting one or two or more combinations optimal for the control of the warp, each of the selected control to eliminate the warp amount from the warp amount at the tip of the material 16 to be rolled. Calculate the control value, the cooling water flow rate control device 22, in the next pass based on each calculated control value,
It is configured to control the main machine control device 26 and the hydraulic pressure reduction control device 30. Next, a method of calculating a control value in each control for eliminating the warp amount from the warp amount at the tip of the material 16 to be rolled in the process computer 40 will be described. FIG. 4 shows the case where the tip of the rolled material 16 exhibits upward warp, and FIG. 5 shows the case where the tip of the rolled material 16 exhibits downward warp. The radius of curvature in this warped state is ρ, and in the case of upward warp, its sign is positive, and in the case of downward warp, its sign is negative. Figure 6 is a different speed ratio of the upper and lower work rolls _{(V 1 -V 2) / V} 1
It shows the relationship between × 100 and the curvature of curvature k ₁ (1 / ρ), that is, the effect of the different speed rates of the upper and lower work rolls on the plate warp. In addition, V ₁ indicates the rotation speed of the upper work roll, and V ₂ indicates the rotation speed of the lower work roll. As is clear from the figure, when the differential speed increases, the tip of the material 16 to be rolled tends to warp along with this, and the curvature k ₁ thereof tends to increase as the differential speed increases. Different speed ratio of upper and lower work rolls (V ₁
The relationship between −V ₂ ) / V ₁ × 100 and the curvature of curvature k ₁ (1 / ρ) is expressed by the following equation. k ₁ = α ₁ · f ₁ {(V ₁ −V ₂ ) / V ₁ × 100} (3) where α ₁ = g ₁ (ld / km). That is, α ₁ is obtained by the function g ₁ based on the ratio ld / hm between the contact arc length ld and the average plate thickness hm. Therefore, due to the difference in the number of rotations of the upper and lower work rolls, k ₁
When the plate warps with a warp curvature of, the control value (V ₁ −V ₂ ) / V _{1 at} which the warp curvature k ₁ becomes zero in the next pass.
× 100 can be obtained from the above equation (3). FIG. 7 shows the lower roll pickup amount H and the warp curvature k.
₂ (1 / ρ), that is, lower roll pick-up amount H
This shows the effect of the on the warp. As is clear from the figure, when the lower roll pick-up amount H increases, the tip of the rolled material 16 also warps, and its warp curvature | k ₂ | increases with the lower roll pick-up amount H. Shows an increasing tendency. From FIG. 7, the lower roll pickup amount H and the warp curvature are
The relationship with k ₂ is expressed by the following equation. k ₂ = α ₂ · f ₂ (H) (4) where α ₂ = g ₂ (ld / hm). That is, α ₂ is a value obtained from the function g ₂ based on the ratio ld / hm between the contact arc length ld and the average plate thickness hm. Therefore, when the plate warps due to the warp curvature of k _{2 due} to the lower roll pick-up amount H, the control value H at which the curvature becomes zero in the next pass should be obtained from the equation (4). You can FIG. 8 shows the relationship between the vertical impact drop amount difference Xn ₁ −Xn ₂ and the warp curvature k ₃ , that is, the vertical impact drop amount difference Xn.
_This shows the effect of _1- Xn ₂ on plate warpage. Note that Xn ₁ indicates the upper impact drop amount, and Xn ₂ indicates the lower impact drop amount. As is clear from the figure,
When the difference in vertical impact drop amount increases, the tip of the rolling mill 16 is warped and the warp curvature is increased.
| k ₂ | tends to increase as the difference in vertical impact drop increases. From this FIG. 8, the difference in the amount of vertical impact drop Xn ₁ −Xn ₂
And the curvature of curvature k ₃ is expressed by the following equation. k ₃ = α ₃ · f ₃ (Xn ₁ −Xn ₂ ) (5) where α ₃ = g ₃ (ld / hm). That is, α ₃ is a value obtained from the function g ₃ based on the ratio ld / hm between the contact arc length ld and the average plate thickness hm. Accordance connexion, vertical impact drop class tap weight difference Xn ₁ Yotsute to -Xn _2, when connexion plate is counter-one in k ₃ becomes warped curvature, in the next pass, the control value Xn ₁ -Xn whose curvature becomes zero ₂ can be obtained from the above equation (5). FIG. 9 shows the relationship between the temperature difference T ₁ -T ₂ between the upper and lower surfaces of the rolled material 16 and the warp curvature k ₄ , that is, the effect of the temperature difference between the upper and lower surfaces of the rolled material 16 on the plate warpage. is there. As is clear from the figure, as the temperature difference T ₁ -T ₂ between the upper and lower surfaces of the material 16 to be rolled increases, the tip of the material 16 to be rolled becomes warped, and its curvature of curvature | k ₄ | It shows a tendency to increase as the temperature difference T ₁ −T ₂ increases. From FIG. 9, the relationship between the upper and lower surface temperature difference T ₁ -T _{2 of the} rolled material and the warp curvature k ₄ is expressed by the following equation. k ₄ = α ₄ · f ₄ (T ₁ −T ₂ ) ... (6) where α ₄ = g ₄ (ld / hm). That is, α ₄ is a value obtained from the function g ₄ based on the ratio ld / hm between the contact arc length ld and the average plate thickness hm. Therefore, by the upper and lower surface temperature difference T ₁ -T ₂ of the material 16 to be rolled,
When the plate warps with a warp curvature of k _{4, the} control value T ₁ -T _{2 at} which the warp curvature becomes zero can be obtained from the above equation (6) in the next pass. Next, the selection of the optimum combination of the controls in the process computer 40 will be described. The selection of the optimum combination of the respective controls is made based on a quantitative elucidation result of the influence of various factors causing the plate warp on the vertical warp of the plate by the present inventor. Specifically, the optimum combination of each control is selected based on the quantitative understanding of the factors causing the plate warp as shown below. First, with respect to the cause of tip nose bending shown in (C) to (E) of FIG. 16 above, the influence of the difference in vertical impact drop amount is particularly large. Therefore, it is understood that it is desirable to appropriately control the difference in impact drop amount when the tip nose bend occurs. FIG. 10 shows the effect of the ratio ld / hm on the relationship between the differential speed ratio and the warp curvature shown in FIG. FIG. 11 shows the effect of the ratio ld / hm on the relationship between the upper and lower surface temperature difference of the material 16 to be rolled and the warp curvature shown in FIG.
As is clear from FIG. 10, the ratio ld / hm is the predetermined value A
_It can be seen that when the velocity is within the range of ₁ and A ₂ (A ₁ <ld / hm <A ₂ ), the differential velocity ratio has little influence on the warp. Also, the eleventh
As is clear from the figure, when the ratio ld / hm is within the range of predetermined values A ₁ and A ₂ (A ₁ <ld / hm <A ₂ ), the material to be rolled 16
It can be seen that the upper and lower surface temperatures have a large effect on the warpage. Therefore, when the ratio ld / hm is within the range of the predetermined values A ₁ and A ₂ , it is understood that the temperature difference control or the pick-up amount control is effective for the warpage control of the rolled material 16. Further, in the forming pass, it is difficult to control the pick-up amount due to rolling problems. Therefore, in the present embodiment, based on the warp amount and the warp shape obtained from the warp sensor 32, whether or not the nose is bent,
Whether there is a change in the direction of warp, whether it is a molding pass, the ratio
By determining whether or not ld / hm is within the range of predetermined values A ₁ and A ₂ , the rotation speed control of the upper and lower work rolls, the pick up amount control of the lower work roll, the upper and lower impact drop amount. Of the control and the temperature difference control between the upper and lower surfaces of the rolled material, one or more combinations optimal for warpage control are selected. This choice is specifically the 12th
This is based on the flow chart shown in the figure. That is, in step 100, the warp sensor 32 detects the warp amount and the warp shape. Next, in step 102, it is determined whether or not the warp shape obtained from the warp sensor 32 is a nose bend shape. If it is determined in step 102 that the warp shape is a bent nose shape, the process proceeds to step 104. In step 104, it is determined whether or not there is a change in the direction of warpage. If it is determined in step 104 that there is a change in the direction of the warp, the process proceeds to step 106. In step 106, it is judged whether or not it is a molding pass. If it is determined in step 106 that it is the molding pass, the process proceeds to step 108. In step 108, the ratio ld / hm is set to a predetermined value A ₁ , A ₂
It is determined whether it is between. If it is determined in step 108 that the ratio ld / hm is within the predetermined range A ₁ <ld / hm <A ₂ , the process proceeds to step 110. In step 110, select the impact drop amount control and the upper and lower surface temperature difference control of the material 16 to be rolled, which is the optimum control for the warp shape and the path divided by the processing of steps 102 to 108, These two selected controls are combined. Next, in step 112, it is determined whether or not the rolling is completed. If it is determined to be positive in this step 112, that is, if it is determined to be the end of rolling, the program ends. On the other hand, if the result of the determination in step 112 is negative, that is, if it is determined that the rolling has not been completed, the process returns to step 100. Further, in the above-mentioned step 108, the ratio ld / hm is a predetermined value.
If it is determined that it is not between A ₁ and A ₂ , the process proceeds to step 114. In step 114, the impact drop amount control and the rotation speed control of the upper and lower work rolls are selected,
These respective controls are performed in combination. On the other hand, if it is determined in the above-mentioned step 106 that it is not the molding pass, the process proceeds to step 118. At step 118, it is determined whether the ratio ld / hm is between the predetermined values A ₁ and A ₂ . In step 118, the ratio ld / hm is within the predetermined range A ₁ <ld
If it is determined that / hm <A ₂ , the process proceeds to step 120. In step 120, the impact drop amount control, the pick up amount control, and the upper / lower surface temperature difference control of the material to be rolled are selected, and these controls are combined. If the result of the determination at step 118 is negative,
That is, when it is determined that the ratio ld / hm is not within the predetermined range A ₁ <ld / hm <A ₂ , the process proceeds to step 122. In step 122, impact drop amount control, work roll rotation number control, and pick up amount control are selected, and these controls are combined. Further, if it is determined in the above step 104 that the result is no, that is, if there is no change in the direction of the warp, the process proceeds to step 116. At step 116, the impact drop amount control is selected and this control is performed. If it is determined to be no in the above step 102,
That is, if it is determined that the nose is not bent, step 12
Go to 4. In step 124, it is judged whether or not it is a molding pass. If it is determined in step 124 that it is a molding pass, the process proceeds to step 126. In step 126, the ratio ld / hm is within the predetermined range A ₁
It is determined whether or not <ld / hm <A ₂ . If it is determined in step 126 that the ratio ld / hm is within the predetermined range, the process proceeds to step 128. In this step 128, upper and lower surface temperature difference control of the material 16 to be rolled is selected and this control is performed. If the result of the determination in step 126 is negative,
That is, if it is determined that the ratio ld / hm is out of the predetermined range, the process proceeds to step 130. In step 130, the work roll rotation speed control is selected and this control is performed. If the result of the determination at step 124 is negative,
That is, when it is determined that the molding pass is not performed, the step
Continue to 132. In step 132, it is determined whether the ratio ld / hm is within a predetermined range A ₁ <ld / hm <A ₂ as in step 126. In this step 132, the ratio ld / hm is within the predetermined range A ₁
If it is determined that <ld / hm <A ₂ , then step 134
Proceed to. In step 134, the upper / lower surface temperature difference control of the material to be rolled and the pick-up amount control are selected, and these controls are combined. If the result of the determination at step 132 is negative,
That is, when it is determined that the ratio ld / hm is not within the predetermined range, the routine proceeds to step 136. In this step 136, the work roll speed control and the pick-up amount control are selected, and these controls are combined. Therefore, according to the present embodiment, based on the information on the amount of warp and the shape of the warp obtained from the warp sensor 32, whether or not the nose bend shape, whether there is a change in the direction of the warp, whether or not the molding path, It is possible to determine whether the ratio ld / hm is within a predetermined range, analyze the shape of the warp or the like by each of these judgments, and select various warp correction control optimal for each warp shape. This makes it possible to perform optimum warp correction control corresponding to various warp shapes. In particular, in the case of the present invention, since various controls are performed in consideration of the ratio ld / hm, it is possible to cope with changes in the plate thickness and the reduction ratio, and it is possible to efficiently suppress the warp of the plate. . FIG. 13 shows the results of the implementation of this embodiment in comparison with those without the warp correction control. The figure (A) shows the results of the practice of this example, and the warp curvature after rolling could be suppressed to within ± 1 × 10 ⁻⁴ (mm ⁻¹ ). On the other hand, FIG. 6B shows the case where the warp correction control is not performed, and in this case, the warp curvature after the rolling end is within ± 2.5 × 10 ^-4 (mm ^-1 ). ing. From this, it can be seen that in the case of the present embodiment, the warp curvature variation range can be made smaller than that in the case where the warp correction control is not performed, and the optimum warpage control is performed.

【The invention's effect】

As described above, according to the present invention, it is possible to select the most effective warp control means for the warp control according to the rolling conditions from among the various warp control means, and efficient control can be performed. It has an excellent effect that it becomes possible.

[Brief description of drawings]

FIG. 1 is a flow chart showing the gist of a method for controlling plate warpage in plate rolling according to the present invention, and FIG. 2 is a diagram for explaining an example of a known method for obtaining a contact arc length and an average plate thickness, FIG. 3 is a side view including a partial block diagram showing a plate rolling facility for implementing the plate warpage control method for plate rolling according to the present invention, and FIG. 4 shows the warpage of the rolled material. Side view, FIG. 5 is a side view showing the warp of the material to be rolled, FIGS. 6 to 11 are for explaining the principle of the present invention, and FIG. And FIG. 7 is a diagram showing the relationship between the pick-up amount and the warp curvature, FIG. 8 is a diagram showing the relationship between the impact drop amount and the warp curvature, FIG. 9 is a diagram showing the relationship between the upper and lower surface temperature difference of the material to be rolled and the warp curvature, and FIG. Fig. 11 shows the effect of the ratio ld / hm on the relationship between the temperature difference between the upper and lower surfaces of the material to be rolled and the warp curvature. FIG. 12 is a flow chart showing the control of the embodiment of the plate warpage control method in the thick plate rolling according to the present invention, and FIG. 13 is a diagram showing the execution results of the embodiment in comparison with the uncontrolled one, FIG. 14 is a side view for explaining the pick-up, FIG. 15 is a diagram for explaining the impact drop, and FIG. 16 is a side view showing examples of various warp shapes. 10, 11 …… Work roll, 12,13 …… Back up roll, 14 …… Reverse rolling mill, 16 …… Rolling material, 18A, 18B, 20A, 20B …… Cooling device, 22 …… Flow control device, 26 …… Main machine control device, 30 …… Hydraulic pressure reduction control device, 32 …… Warp sensor, 34 …… Microcomputer, 36,38 …… Thermometer, 40 …… Process computer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Nishizaki 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (No house number) Inside the Mizushima Works, Kawasaki Steel Co., Ltd. Chome (no address) Kawasaki Steel Co., Ltd. Mizushima Steel Works (56) Reference JP-A-57-88909 (JP, A) JP-A-59-178114 (JP, A) Practical use Sho-59-129409 (JP, U) )

Claims (1)

[Claims] 1. The upper and lower ends of a plate based on a warp amount and a warp shape measurement result of a warp sensor installed on at least one of front and rear surfaces of a rolling mill of a thick plate rolling equipment and quantifying the vertical warp of the thick plate. In the plate warpage control method in plate rolling that corrects warpage, it is determined whether or not it is a forming pass, and the ratio between the contact arc length of the material to be rolled and the average plate thickness of the material to be rolled is calculated. Whether or not and based on the ratio, the rotation speed control of the upper and lower work rolls, the pickup amount control of the lower work roll, the upper and lower impact drop amount control, and
A method for controlling plate warpage in thick plate rolling, characterized by selecting either the upper or lower surface temperature difference control of the thick plate or a combination thereof.